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commit 4eaf431f6f71bbed40a4c733ffe93a7e8cedf9d9 upstream. syzbot has triggered a NULL ptr dereference when allocation fault injection enforces a failure and alloc_mem_cgroup_per_node_info initializes memcg->nodeinfo only half way through. But __mem_cgroup_free still tries to free all per-node data and dereferences pn->lruvec_stat_cpu unconditioanlly even if the specific per-node data hasn't been initialized. The bug is quite unlikely to hit because small allocations do not fail and we would need quite some numa nodes to make struct mem_cgroup_per_node large enough to cross the costly order. Link: http://lkml.kernel.org/r/20180406100906.17790-1-mhocko@kernel.org Reported-by: syzbot+8a5de3cce7cdc70e9ebe@syzkaller.appspotmail.com Fixes: 00f3ca2c2d66 ("mm: memcontrol: per-lruvec stats infrastructure") Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.